The fruit body has a 5.5–10 cm diameter cap that has a texture reminiscent of suede or chamois and can be sticky when young. Initially orange- or pinkish-brown, it is subconical with a thickened margin, and flattens with age and fades an ochre colour. Like other boletes, it has tubes under the cap instead of gills. These are white in young specimens maturing to pink. The cylindrical white stipe is 7–16 cm tall and 1.7–2.5 cm wide, marked with deep lacunae.^[3] The white flesh bruises yellowish and has a bitter taste. The edibility is unknown. The spore print is brown, the spores 15–19 x 5–6.5 μm and covered entirely with warty lumps.^[1]

A. occidentalis establishes a new type of plant-fungus symbiosis with jarrah (Eucalyptus marginata), which has been described recently. The presence of A. occidentalis is associated with increased growth and nutrient uptake in jarrah seedlings, despite the fact that mycorrhizal structures were not recovered from the roots of the eucalypt (no root colonization). Chemical and genetic analysis of the soil and plants showed that fungal hyphae were nearby the roots and that plants had increased levels of nutrients including phosphorus, nitrogen, sulphur, magnesium, and several trace elements. Furthermore, the 33P uptake study revealed that fungal hyphae do not transfer nutrient directly to plants. Mobilization and solubilization of nutrients from minerals and soil particles could be one of the underlying mechanisms as the concentration of carboxylates in the rhizosphere soil is higher in plants involved in this symbiosis. However, there might be other unknown mechanisms behind the remarkable improvements in plant growth and nutrition.^[4]

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